Data Input
In order to input the required information for this pollutant into the Water Quality model, the user needs to make sure that the Tab Diffusion appears in the WQ General Tab (please follow the description on the page Preparing a Water Quality Datafile for this). Then the user needs to select the Tab Diffusion and type in the necessary information for this pollutant in the fields which are shown on this Tab. Alternatively the necessary information for this pollutant can be typed in the .con file opened in a Textpad editor in the datafile format mentioned below.
Datafile format
Depending on the form of dispersion coefficient which the user wishes to simulate there are five different data formats.
For constant diffusion everywhere within the model use:
Line 1 DIFFUSION
Line 2 CONSTANT
Line 3 d0
Where:
DIFFUSION = keyword
CONSTANT = keyword
d0= Value of constant dispersion coefficient, D0(m2/s).
For a variable value of the constant diffusion coefficient use:
Line 1 DIFFUSION
Line 2 VARIABLE
Line 3 label, d0
Above line is repeated for each node in the model.
Where:
DIFFUSION = keyword
VARIABLE = keyword
label = Node label
d0 = Value of constant dispersion coefficient, D(m2/s).
For estuary type diffusion use:
Line 1 DIFFUSION
Line 2 ESTUARY
Line 3 azero, uzero, szero, dzero
Line 4 d0, d1, d2
Where:
DIFFUSION = keyword
ESTUARY = keyword
label = Node label
d0 = Value of constant dispersion coefficient, D(m2/s).
azero = Representative cross-sectional area at seaward boundary (m2)
uzero = peak tidal velocity at seaward boundary (m/s)
szero = salinity at seaward boundary (ppt)
dzero = representative saline intrusion length (km).
d0, d1, d2 = Value of empirical longitudinal dispersion coefficients D, Dand D(m2/s).
For river applications use:
Line 1 DIFFUSION
Line 2 RIVER
Line 3 d0, d1
Where:
DIFFUSION = keyword
RIVER = keyword
d0, d1 = Value of longitudinal dispersion coefficients D(m2/s) and D
Where the user wishes to use different types of dispersion coefficients in different parts of the model use:
Line 1 DIFFUSION
Line 2 DYNAMIC
Line 3 azero, uzero, szero, dzero
Line 4 Label, type, d0(n), d1(n), d2(n)
Line 4 is repeated for each node.
Where:
DIFFUSION = keyword
DYNAMIC = keyword
azero = Representative cross-sectional area at seaward boundary (m2)
uzero = peak tidal velocity at seaward boundary (m/s)
szero = salinity at seaward boundary (ppt)
dzero = representative saline intrusion length (km).
Label, type, d0(n), d1(n), d2(n) = Node label, diffusion type (keyword 'RIVER' or 'ESTUARY'), value of longitudinal dispersion coefficients D, Dand D(m2/s). (If type = 'RIVER' then D2 is not used and should be set to zero by the file editor).
Overview
Diffusion